PLK4 Protein

PLK4 Protein (Polo-Like Kinase 4)

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<tr><th colspan="2" style="background:#e8f0f8; text-align:center; font-size:1.1em;">PLK4 Protein</th></tr>
<tr><td><strong>Protein Name</strong></td><td>Polo-Like Kinase 4</td></tr>
<tr><td><strong>Gene</strong></td><td>[PLK4](/genes/plk4)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q9Y5A9](https://www.uniprot.org/uniprot/Q9Y5A9)</td></tr>
<tr><td><strong>Alternative Names</strong></td><td>Sak, Snk, Serine/threonine-protein kinase PLK4</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>~97 kDa</td></tr>
<tr><td><strong>Subcellular Localization</strong></td><td>Centrosome, nucleus</td></tr>
<tr><td><strong>Protein Family</td><td>Polo-like kinase family</td></tr>
<tr><td><strong>Enzyme Classification</strong></td><td>EC 2.7.11.1 (Protein kinase)</td></tr>
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<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
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Overview

PLK4 Protein (Polo-Like Kinase 4)

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f0f8; text-align:center; font-size:1.1em;">PLK4 Protein</th></tr>
<tr><td><strong>Protein Name</strong></td><td>Polo-Like Kinase 4</td></tr>
<tr><td><strong>Gene</strong></td><td>[PLK4](/genes/plk4)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q9Y5A9](https://www.uniprot.org/uniprot/Q9Y5A9)</td></tr>
<tr><td><strong>Alternative Names</strong></td><td>Sak, Snk, Serine/threonine-protein kinase PLK4</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>~97 kDa</td></tr>
<tr><td><strong>Subcellular Localization</strong></td><td>Centrosome, nucleus</td></tr>
<tr><td><strong>Protein Family</td><td>Polo-like kinase family</td></tr>
<tr><td><strong>Enzyme Classification</strong></td><td>EC 2.7.11.1 (Protein kinase)</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Overview

PLK4 (Polo-Like Kinase 4) is a serine/threonine protein kinase belonging to the Polo-like kinase family. Originally identified as a key regulator of centriole duplication and cell division, PLK4 has more recently been implicated in [neurodegenerative diseases](/diseases/alzheimers-disease) including [Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), and [Amyotrophic Lateral Sclerosis (ALS)](/diseases/als). PLK4 is unique among Polo-like kinases in its role in governing centrosome biology and its involvement in neuronal survival pathways.

Structure and Function

Kinase Domain Architecture

PLK4 contains several functional domains:

• N-terminal kinase domain: Catalytic serine/threonine kinase activity
• Polo-box domains (PBD): Two polo-box motifs that recognize phosphorylated substrates
• Leucine zipper: Mediates protein-protein interactions
• Dynein light chain binding site: Enables microtubule-based transport

Substrate Specificity

PLK4 phosphorylates key substrates involved in:

• Centriole duplication: STIL, SAS6, and CPAP
• Cell cycle regulation: CDK1/Cyclin B substrates
• DNA damage response: ATR/Chk1 pathway components
• Microtubule organization: Pericentriolar material proteins

Role in Neurodegeneration

Alzheimer's Disease

PLK4 dysregulation in AD relates to:

• [Tau](/proteins/tau) phosphorylation: PLK4 can phosphorylate tau at disease-relevant sites
• Cell cycle re-entry: Neuronal cell cycle abnormalities in AD involve PLK4
• Centrosome dysfunction: Abnormal centrosomes in AD [neurons](/entities/neurons)
• DNA damage response: PLK4 activation in stressed neurons

Parkinson's Disease

In PD, PLK4 participates in:

• Alpha-synuclein phosphorylation: PLK4 can phosphorylate [alpha-synuclein](/proteins/alpha-synuclein) at Ser129
• Dopaminergic neuron survival: PLK4 is protective in [substantia nigra](/brain-regions/substantia-nigra) neurons
• Mitophagy: PLK4 involvement in mitochondrial quality control
• Stress response: PLK4 activation in cellular stress models

Amyotrophic Lateral Sclerosis

In ALS, PLK4 has been studied for:

• [TDP-43](/mechanisms/tdp-43-proteinopathy) pathology: PLK4 may phosphorylate TDP-43
• Motor neuron survival: PLK4 activity affects motor neuron viability
• Protein aggregation: Interactions with aggregation-prone proteins

Molecular Mechanisms

PLK4 contributes to neurodegeneration through:

Therapeutic Implications

Kinase Inhibitors

PLK4 is a potential drug target:

• ATP-competitive inhibitors: Small molecules targeting the kinase domain
• Allosteric modulators: Compounds targeting regulatory domains
• Substrate-directed inhibitors: Molecules blocking PLK4-substrate interactions

Biomarker Potential

PLK4 activity may serve as:

• Disease progression marker: PLK4 levels correlate with disease stage
• Therapeutic response indicator: Treatment effects on PLK4 activity
• Risk stratification: PLK4 genetic variants and disease risk

Clinical Relevance

Genetic Associations

PLK4 polymorphisms have been studied in:

• Neurodegenerative disease risk: Some associations reported
• Cancer predisposition: Biallelic mutations cause microcephaly
• Developmental disorders: PLK4 haploinsufficiency affects brain development

Clinical Trials

No PLK4-targeted therapies are currently in clinical trials for neurodegenerative diseases, though:

• Preclinical studies: PLK4 inhibitors show promise in models
• Repurposing potential: Existing oncology drugs may be repurposed

See Also

• Cell Cycle in Neurodegeneration
• Tau Phosphorylation Pathways
• Centrosome Dysfunction in Neurodegeneration
• Alpha-Synuclein Phosphorylation

References